More Details on Forest Tent Caterpillar Forest tent caterpillar defoliated areas mapped during 2016 aerial surveys are now available

on the ANR Natural Resources Atlas. The layer is called “Forest Tent Caterpillar (2016)” and is available under the “Forests, Parks and Recreation” theme. To view the data, click on

“Layers” at the bottom of the left hand sidebar. Click the “+” sign next to Forests, Parks and Recreation. And then click on “Forest Tent Caterpillar (2016)”. To see the Legend, click the

icon between the check box and the layer name. Users are reminded that this information is

acquired at speeds of over 100 mph and may be incomplete, since observers can’t see under the plane or behind some of the hills.

The defoliated area is likely to increase in 2017. Moth catches in all but one of our phero-

mone trap locations increased from 2015, with the statewide average trap catch in double digits for the first time since 2006.

It bears repeating that our VT FPR Forest Tent Caterpillar Update has been revised to include

recent observations, describing the current status of forest tent caterpillar, and providing management information for sugar makers, forest land managers, and others concerned

about protecting tree health.

Vermont Forest Health

Insect and Disease

Observations—September 2016

Department of Forests, Parks & Recreation

September 2016 vtforest.com

Forest tent caterpillar moth catches increased in 12 of our 13 pheromone trap survey

locations. The statewide average in 2016 was 12.5 moths per trap.

All Tied Up In some areas, larvae of the beech leaftier (the immature stage of a moth in the genus

Psilocorsis) have been busy. These insects are members of the Family Oecophoridae, known commonly as the “concealer moths” because larvae feed concealed in webs or in

rolled or tied leaves of the host plant. When full grown, larvae drop to the ground and crawl under fallen leaves, where they overwinter as pupae.

Ash (not so pretty) Flower Gall

Distorted, distinctive galls observed on ash are the result of a tiny eriophyid mite known as the ash flower gall mite. Though the health of the tree is unaffected, the galls can make a

tree look unsightly.

(Left) Young beech leaftier larvae feed together and skeletonize leaves. (Right) As

they mature, larvae feed alone from within their leaf shelters. Photo: J. Frye

(Left) Mites initiate gall growth early in the spring. (Right) During late summer

the galls turn dark brown and woody, and can remain on the tree for more than one season. Photos: R. Kelley (left); J. Esden (right)

We’re Still Dry

September began as abnormally dry for most of the state and by mid-month, drought conditions expanded to include the Champlain Valley and most of southern Vermont.

Temperatures were warmer than normal and precipitation below normal for the month.

Streamflow data from the USGS WaterWatch indicate that rivers are running below to much

below normal in a large part of the state, and that Lake Champlain’s water level is below normal at 93.87 feet. In some areas, dry conditions may affect hay and corn crops but re-

ports indicate that the drought has had little impact on apple orchards. According to news reports, many orchards are reporting a good apple crop this year, and the fruit in many

cases is bigger than in years past.

Fire danger indicators (KDBI) are setting record dry levels for soils at the Essex and Danby fire weather stations. This is a concern for ground fires. The potential for higher fire dan-

ger grows as live vegetation cures and leaves drop. A moderate risk of wildland fire has predominated this month and, as fall progresses, these factors

can keep fire danger high.

Drought effects were likely to have been the “last straw” lead-

ing to occasional mortality of trees that were already stressed, for example elms with Dutch elm disease, blue spruce repeat-

edly defoliated by Rhizosphaera needlecast, and shallow-rooted landscape trees. There has also been an increase in interior

needle drop of conifers and premature leaf drop of ash and oth-er hardwoods where trees are under stress from drought.

Despite (or perhaps because of) drought conditions (see August

Update), fall foliage has been particularly stunning in some are-as, with lots of reds.

Hemlock showing interior needle yellowing symptomatic of drought. Photo: D. Dillner

Dry conditions prevailed in September, with above normal temperatures and

below normal rainfall.

Scaling Up

Many trees and shrubs are host to scale insects. Scales ingest plant fluids by inserting their piercing/sucking mouthparts into leaves, twigs, fruits, or the trunk of the tree. Some, like

the magnolia scale, are host-specific and others, like oystershell scale, are polyphagous, feeding on a variety of species. Some scales can cause serious damage while others may go

unnoticed. Scales like the cottony maple scale and the pine needle scale have conspicuous ovisacs and/or waxy coverings. On the other hand, Matsucoccus scales, like the red pine

scale, are more cryptic, wedged in bark crevices for much of their lifespan.

Life cycles of scales tend to be complex. Most adult females are wingless and often legless,

and lay eggs under a protective cover or within an egg sac. First instar nymphs, often re-ferred to as “crawlers,” are mobile and can move to a suitable location to settle and feed.

Crawlers may also be wind-dispersed or moved to new sites on the feet of birds and other organisms. Male scales, rarely observed, are winged, short-lived, and resemble small gnats.

What is the actual cause of death when scales attack trees? Here are two examples:

Beech scale, like some other scales, teams up with a fungus (Nectria spp.) and the resulting “beech bark disease” kills or injures American beech. When trees are attacked by beech

scale, sometimes the bark forms a wound periderm and walls off the injury. In those cases, any Nectria infection is superficial. It may disfigure the bark but is not a cause of mortality.

However, when the wound periderm does not wall off the injury, Nectria can infect and kill the cambium. If there are multiple infections and/or tree resistance is poor (e.g. due to

drought stress) cambium mortality is enough to kill the tree.

Red pine scale sucks sap from the phloem parenchyma of shoots, preferably the 3-year old portion, “causing desiccation and dieback of branches and tree death within 2 to 5 years”,

according to a publication by Mark McClure. As of 1991 when the publication was written,

the exact mechanism was unknown. It does explain that the saliva of other species which feed on the cortical parenchyma triggers “an imbalance in plant growth hormones, causing

structural modification of the xylem, restriction of water uptake by the sapwood, and rapid desiccation and death of the tree.” See http://www.nrs.fs.fed.us/pubs/gtr/gtr_ne153/

gtr_ne153_256.pdf for more information.

(Left) Magnolia scales secrete a large amount of honeydew which, in turn, promotes the

growth of sooty mold on nearby surfaces; (Center) Oystershell scales feed on lilac, beech, birch, ash, maple, poplar, willow, elm, apple, and other trees; (Right) The cyst stage of

red pine scale, Matsucoccus matsumarae, on a red pine sample. Photo: B. Guenther (left), R. Kelley (center), Maine Forest Service (right).

Scales to Watch Out For The black pineleaf scale, Dynaspidiotus californica (formerly Nuculaspis californica) was

brought to our attention recently when it was observed on needles of Austrian pine in northeastern Windsor County. Though we didn’t have any records of this scale in our FPR

database, the insect has been found in nearby states, so observing it in Vermont would not be too surprising. The black pineleaf scale is apparently native to North America and

has not been recorded elsewhere. Johnson and Lyon (in Insects That Feed on Trees and

Shrubs) wrote: “Known in virtually all areas of the United States and Canada where sus-ceptible hosts occur, the black pineleaf scale has only occasionally inflicted sufficient dam-

age to be considered an important pest…”

We’ve been alerted to be on the lookout for the coniferous fiorinia scale (Fiorinia japonica), which has never been reported in Vermont. This non-native insect feeds on the upper and

lower surface of foliage of a variety of conifers. Little is known about its distribution or po-tential damage. This insect may be mistaken for the elongate hemlock scale (Fiorinia ex-

terna), which generally feeds on the lower surface of needles. In Vermont, the elongate scale is only known to be established in southeastern Windham County, where it was first

found by a Forest Pest First Detector in 2014.

Cold temperatures and parasitism are thought to be limiting factors of black pineleaf scale. For addi-

tional photos, see http://www.forestryimages.org/browse/subthumb.cfm?sub=323. Photo: G. Maia

(Left) Coniferous fiorinia scale, also known as Japanese fiorinia scale, feeds on upper and

lower surfaces of needles; (Right) Elongate hemlock scale was discovered in Vermont in 2014 by a First Detector. Photos: (Left) G. Arakelian, (Right) J. Weimer

Steeplebush look-a-like is an early detection invasive

A member of the rose family (Rosaceae), False spiraea (alt. false spirea) (Sorbaria sorbifo-lia) has a native range in the more northerly climes of Asia (northern China, Korea, Japan,

Siberia). It is a shrub, and can be found in forest edges, meadows, fields, and disturbed areas. The presence of this species tends to be related to human settlement and landscap-

ing, but local populations become very dense and impact the ability of native species to grow or regenerate.

False spiraea is spread throughout the northeastern US and eastern Canadian provinces,

and in places along the West Coast and Alaska. Cornell University’s Woody Plants Data-base considers this plant to be hardy to zone 3a. It has been mapped across New England,

into Pennsylvania and points west. In Vermont, populations are isolated but expanding lo-cally, with well-developed populations in numerous counties, and in sensitive areas like

the Green Mountain National Forest and the Northeast Kingdom.

False spiraea is currently considered moderately invasive in Southern Ontario, and is iden-

tified as having invasive tendencies by the Adirondack Park in New York. It is soon to be added to the watch list in Vermont, meaning the plant has invasive tendencies, but is not

yet prohibited. This plant is considered an early detection invasive species in Vermont, as there are several accounts of the spread of this plant in the state, but it is not yet well es-

tablished.

The best time to identify this plant is during the late summer, when it is flowering. The flowers are tall panicles, similar in appearance to the native white or rosy meadowsweets

(Spiraea alba, Spiraea tomentosa), and is where it gets its common name of “false spi-raea”.

To learn more, check out the USDA NRCS Plants Database, Cornell University’s Woody

Plants Database, Wisconsin DNR, Southern Ontario Urban Forests Associates, Urban Forest Associates Inc., Credit Valley Conservation, Ontario, Invasive Plant Council of New York

State, NY Non-native Plant Invasiveness Ranking Form, New Jersey Conservation Founda-

tion ), and the Invasive Plant Atlas of New England.

False spiraea foliage

(left) and pyramid-shaped panicles of white

flowers (right). Photos: R. Vidéki at Bugwood

(left) A. Haines at GoBot-any right)

For more information, contact the Forest Biology Laboratory

at 802-879-5687 or:

Windsor & Windham Counties…………………………………………… Bennington & Rutland Counties………………………………………… Addison, Chittenden, Franklin & Grand Isle Counties……… Lamoille, Orange & Washington Counties………………………… Caledonia, Orleans & Essex Counties…………………………………

Springfield (802) 885-8845 Rutland (802) 786-0060 Essex Junction (802) 879-6565 Barre (802) 476-0170 St. Johnsbury (802) 751-0110

Forest health programs in the Vermont Department of Forests, Parks and Recreation are supported, in part, by the US Forest Service, State and Private For-

estry, and conducted in partnership with the Vermont Agency of Agriculture, Food and Markets, USDA-APHIS, the University of Vermont,

cooperating landowners, resource managers, and citizen volunteers. In accordance with Federal law and U.S. Department of Agriculture policy, this institution

is prohibited from discrimination on the basis of race, color, national origin, sex, age, or disability.

2016-08

Odds and Ends Hemlock woolly adelgid: The publication entitled Biology and Control of Hemlock Woolly

Adelgid by Havill et. al. has recently been updated.

Bee keepers: For some, this has been an excellent summer for honey bees. One keeper reported taking 180 lbs of honey off one hive, and leaving them about 100 lbs for winter.

EAB and crime: A recent report says that EAB infestation was significantly and positively associated with relative increases in some categories of crime, demonstrating another so-

cial cost associated with invasive tree pests.

EAB in Syracuse: A retired Vermont forester who recently visited Syracuse sent some photos reminding us what some classic EAB symptoms look like. The green ash crowns

were completely dead, except for live epicormic growth, mostly towards the base of the crowns.

Pandorus on the prowl: While most sphinx moth caterpillars sport a “horn” over the 8th

abdominal segment, the pandorus sphinx has a thin, whip-like horn that is replaced by a button in the last stage.

Short-winged blister beetles: Adult beetles, often observed in the fall, eat herbaceous

foliage (especially potatoes), while the larvae are parasitic on wild bees.

(Left) EAB-infested street trees in Syracuse NY

showing epicormic growth. Photo: G. Salmon

(Top) Pandorus sphinx

moth caterpillars like this one are sometimes en-

countered as they search for a pupation site. Pho-

to: J. Runcie

(Bottom) If disturbed, blister beetles play dead

by falling on their sides. Photo: B. Boccio